From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750960AbWDUSlg (ORCPT ); Fri, 21 Apr 2006 14:41:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751296AbWDUSlg (ORCPT ); Fri, 21 Apr 2006 14:41:36 -0400 Received: from smtp104.mail.mud.yahoo.com ([209.191.85.214]:27267 "HELO smtp104.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S1750960AbWDUSlf (ORCPT ); Fri, 21 Apr 2006 14:41:35 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=C7cDzgJADuko0P/5lGZOLTAD1mYVkFzfTcfKWybKnfZt1SJ+G4QZLwZJYEmyyAC2HkVQBsVqsgG6HK9uORsyqKwsFM0Qe9HjlbaBYX1yp4pzCxO2oMHJ0EVRyPNEMDNqXAM0/fQ6pycUFADOT11belTqEMN5ZCORTYGA/p6/pu0= ; Message-ID: <4448D8BF.9040601@yahoo.com.au> Date: Fri, 21 Apr 2006 23:06:07 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: David Woodhouse CC: akpm@osdl.org, andrea@suse.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Shrink rbtree References: <1145623663.11909.139.camel@pmac.infradead.org> In-Reply-To: <1145623663.11909.139.camel@pmac.infradead.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi David, Doesn't seem like a bad idea... David Woodhouse wrote: > Our rbtree implementation uses a whole integer for colour information. > In fact, because of alignment constraints on a 64-bit machine it'll be a > whole 64 bits there. We only need a single bit, though -- and we know > the pointers are always going to be aligned. So let's just use the How do we know the pointers are always going to be aligned? IIRC struct address_space needed to be explicitly aligned when doing this trick in page->mapping because some platform byte aligned it. Nick -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com